Answer
$\dfrac{5}{7}$
Work Step by Step
Using order of operations, the expression $
\dfrac{(4-9)+4-9}{10-12\div4\cdot8}
$ simplifies to
\begin{array}{l}
\dfrac{-5+4-9}{10-3\cdot8}
\\\\=
\dfrac{-1-9}{10-24}
\\\\=
\dfrac{-10}{-14}
\\\\=
\dfrac{5}{7}
.\end{array}
